Method for generating and distributing fire extinguishing foam



April 194@. R. M. URQUHART El AL 29 9 METHOD FOR GENERATING AND DISTRIBUTING FIRE EXTINGUISHING FOAM Filed Oct. 18, 1952 2 Sheets-Sheet l \Hmz l RADCUF FE TLURQUHART m Geomzflkmomxkm W' R. M. URQUHART Er ALL 198,585

METHOD FOR GENERATING AND DISTRIBUTING FIRE EXTINGUISHING FOAM Filed Oct. 18, 1932.. 2 Sheets-Sheet 2 RADCUFFEN-URQUHART h AflDGtEORCxEQURQURART 'i atented Apr. 23,1940

PATENT OFFICE METHOD FOR GENERATING AND DISTRIB- UTING FIRE EXTINGUISHING FOAM Radcliffe M. Urquhart, Philadelphia, and George G. Urquhart, Cynwyd, Pa.

Application October 18, 1932, Serial No. 638,272

2 Claims. (Cl. 261-76) This invention relates to improvements in methods for generating and distributing foam for extinguishing fires or for other purposes where a foam blanket may be required, for example, in checking evaporation from volatile liquids. In accordance with the invention a stream of gas is utilized as a foam inducing agent, as distinguished from the conventional type of foamforming method in which chemicals produce a gas within a solution containing a. foam-forming material.

A principal object of the invention is to pro vide a method capable of being carried out by compact, readily portable foam generating equipment. especially adapted for mounting on an automobile truck to be operated by the exhaust gases therefrom or otherwise, and on ships where the foam-forming equipment is to be operated by the stack gases or otherwise, as will be more fully described later. I

Another object of the invention is to provide foam generating methods which can be used in the protection. of oil tanks and the like. Another object of the invention is to reduce the expense of foam generation by avoiding the use of gasproducing chemicals while maintaining the quality of the foam.

Various other objects and advantages of the invention will be apparent from the following description, read in connection with the accompanying drawings, in which-- Reference is made to Patent No. 2,106,043 granted on a division of this application.

Fig. 1 is a vertical section through a preferred type of equipment;

Fig. 2 is a vertical section through an alternative form of the apparatus;

Fig. 3 is a side elevation showing the installation of the equipment on a motor truck; and

Fig. 4 is a side elevation, partly in section, showing the equipment on a steam boat.

Referring first to Fig. 1, reference numeral I indicates a tank adapted to contain an adequate supply of a foam-forming material. This will usually be an aqueous solution of a secondary extract of licorice, extract'of tan bark, saponin, or other suitable substance. These are known, in the trade as stabilizers. The invention is not limited to the use of any particular type of foamforming material. terial has the capacity of being foamed by injecting a gas into its solution or suspension. When reference is made herein to foam-forming material it is understood that this will usually be It is suflicient if the maan aqueous solution, but suspensions or other suitable materials may be used.

The tank I is connected through a pipe 2, in which there is a valve 3, with an ejector chamber 4. Into this chamber there is introduced, through 5 a pipe 5, a stream of water which emerges from a nozzle 6 inside the chamber. The water is forced in under suitable pressure which is supplied by the city mains or by the pump of a fire engine. As the water rushes out of nozzle 6, it causes the foam-forming material to be .drawn in more or less regularly from' the tank I for admixture with the water stream.

In order to provide a larger capacity the pipe 2 may be connected to a branch I in which there 15 is a valve 8 and this branch is connected in turn to an auxiliary source of the foam-forming material. The mixture of water and foam-forming material passes from the ejector chamber 4, preferably through a conical passageway 9, into a pipe 3 10 which is connected to a foam-forming chamber II. It is desirable to pass the foam-forming ,mixture into this chamber through a conical passageway l2 in which there is a spiral l3 or other suitable bafile means which will cause turbulent flow of the mixture and insure good contact with the gas, which is injected through pipe I l. The gasis preferably non-combustible, for example, carbon. dioxide, nitrogen, exhaust gas, flue gas, vapors of carbon tetrachloride, or other non-in- 30 flammable organic compound or the like. How- I ever for some purposes it is permissible to use a gas having some oxygen content, or even air itself. Itis obviously better, however, to use a noncombustible gas for fire extinguishing purposes, 5 as there will inevitably be some decomposition of the foam with release of gas.

The action taking place in the passageway I2 may be described as mechanical subdivision of the foam-forming mixture. This action is not 40 absolutely necessary for the present invention but it is advantageous. The entering gas is distributed in the chamber ll under pressure which may be from 15 to 30 pounds per square inch, orany desired pressure, depending uponthe throw which is desired from the foam nozzle. It is possible to introduce the gas at relatively low pressures (not lower than the nozzle outlet pressure) but better results are obtained by forcing the gas in at higher pressures. The turbulent jet of foam-forming mixture, passing through the chamber ll tends to aspirate and envelope the gas in the path'of, and surrounding, the jet, operatively to form a copious foam which we have found to be satisfactorily stable and tire resistant.

The pressure of the gas is sumcient in general to carry the foam from chamber H through hose i5 and nozzle l6 to the desired distance. However, it is within the scope of the invention to utilize a pump or other means to increase the pressure of the foam. The action taking place in the discharge end of the mixing chamber H and in the hose l5 may be described as a secondary mechanical subdivision of the foe It will be produced in relatively coarse form in the inlet end of chamber H but before it is discharged from nozzle is it will have assumed the necessary fine state of subdivision.

Referring to Fig. 2, the foam-forming material is supplied from a tank I! through a valved line i 8 into the inlet chamber of a pump l9. In the pump the foam-forming material, which is preferably a dilute aqueous solution, is mixed with water entering the pump through aline 20. The mixed water and foam-forming solution pass from the discharge chamber of the pump through a pipe a into the ejector chamber 25. This, as in Fig. l, is connected with a hose or pipe 22 which supplies an auxiliary amount of foam-forming solution if required. Unless the auxiliary supply is needed, a valve 23 in line 22 will be closed and valve 24 in line 25, connected to the discharge chamber of the pump, will be opened. In this case the pump'will deliver the aqueous foamforming material directly to the foam-forming chamberv 26 for discharge through a hose 26a. It will be unnecessary to describe this chamber as it, and its connections, are identical with those shown in Fig.1.

Referring now to Fig. 3, the device of the invention is shown as mounted on a motor truck for actuation by the exhaust gases from the truck engine. While this mode of actuation is most convenient, it is feasible to supply a gas by mounting cylinders of compressed gas on the truck. A tank 21 is arranged on the truck to carry a solution of the foam-forming material. This tank may, for example, have a capacity of about twenty gallons. In another compartment 28 there is stored a larger volume of liquid which may be water without foam-forming substance in it. This compartment may hold about one hundred gallons. The figures are given with reference to an installation on a three to five ton fire truck. Tank 21 is arranged to discharge through a line 28 in which there is a two-way valve 29. This valve communicates respectively with a pipe 30 which leads to the ejector chamber 3| and with a pipe 32 arranged for connection to an auxiliary supply of foam-forming material. Water is supplied to the ejector chamber 3! through a line 33 which can be put in communication with any suitable source of water supply as the pump 33 which takes suction from tank 28. A two-way valve 35 is installed in line 33 for putting it into communication with the ejector chamber 3| or for shutting it oflf therefrom and connecting the line to hose 33a.

The water and foam-forming material pass supplied in tank I, Fig. 1.

iron: the ejector through line 3 to foam-forming chamber 31. Exhaust gases for forming the foam are obtained from the exhaust manifold 38. There is arranged in this a valve 38 which can be operated from the dashboard or other suitable location. when the valve is closed, the exhaust gases will be diverted through branch pipe 40 into the inlet end of the mixing chamber 31. The foam produced in the mixing chamber passes out, under pressure of the exhaust gas, through hose 4| and nozzle 42.

Referring to Fig. 4, the installation is similar to that shown in Fig. 3 but is shown as applied on a steam vessel. Flue gases from the stack 43 are diverted at least in part by closing a valve 44, through branch pipe 45 and pump 3541, into the foam-forming chamber 46. The valve 41 in line 45 is closed when the device is not in operation. It will not be necessary to describe the remaining parts of the equipment since they are identical with those shown in Figs. 1 and 3.

The following specific example will illustrate the operation of the device:

A solution of secondary extract of licorice is When a fire is to be extinguished or other use made of the foamiorzning equipment, water is passed through line 5 under a pressure of, for example, 30 to pounds per square inch. After having opened valve 3 in line 2 the mixture of water and licorice extract is mechanically subdivided in chamber l3 and is subjected to the action of carbon dioxide passed into foam-forming chamber H under a pressure of about 25 pounds per square inch. These conditions will permit the use of a hose of at least feet in length and will, in most cases, give a throw of foam from the nozzle of about 75 feet.

It will be understood that these conditions are given merely for illustration. Various changes and alternative arrangements may be made within the scope of the appended claims in which it is our intention to claim all novelty inherent in the invention as broadly as theprior art permits.

We claim:

1. Method of producing a fire-extinguishing foam which comprises ejecting one or more high velocity streams of liquid from a corresponding number of nozzles in such manner as to impart a high degree of turbulence to the body of said stream of liquid, thereby finely subdividing the same, and aspirating air from the atmosphere into and by means of the resulting stream of subdivided liquid in the presence of a foam promoting agent.

2. Method of producing a fire extinguishing foam,which comprises subdividing a liquid passing from a source of supply to a nozzle outlet, introducing a foam-promoting agent into said liquid, and aspirating air into said liquid, said air being at a pressure not lower than the nozzle outlet pressure.

RADCLIFFE M. URQUHART.

GEORGE G. URQUHART. 

